A demulsifier applicable to ultra-heavy oils with different viscosities, its preparation method and application

Abstract

The present invention provides a demulsifier applicable to super heavy oils with different viscosities, its preparation method and application. The demulsifier has the structure shown in formula (I), and its preparation method includes the steps of: adding methoxypolyethylene glycol acrylate into acetonitrile, heating to the reaction temperature, adding an initiator solution, and then adding butyl acrylate for reaction to obtain. The demulsifier of the present invention has a demulsification effect of over 96% on super heavy oil with a room temperature viscosity of 9.3×10 5 mPa·s and a water content of 30% under the conditions of 80°C for 2 hours and a dosage of 500 ppm. At the same time, for super heavy oil with a room temperature viscosity of 1.5×10 6 mPa·s and a water content of 50%, the demulsification effect can reach over 96% at 80°C for 1 hour. The synthesis steps of the demulsifier of the present invention are simple, the synthesis process does not require a high temperature and high pressure environment, and the monomers have stable properties under normal temperature and pressure, being easy to store and transport, so it has good application value.

Description

Technical Field

[0001] The present invention relates to a demulsifier applicable to ultra - thick oils with different viscosities, its preparation method and application, belonging to the field of oilfield chemistry. Background Art

[0002] With the continuous growth of global energy demand, the availability of conventional or easily recoverable crude oils is becoming increasingly limited, and the development of unconventional heavy oils and ultra - thick oils has received extensive attention. However, due to their inherent high viscosity and low fluidity characteristics, combined with complex reservoir structures, the expected oil recovery process is very challenging. The addition of various oil production aids during oil extraction has led to a continuous increase in the water cut of the produced fluid from oil wells, making the composition and physical properties of the produced fluid more complex, and the emulsion viscosity is also increasing rapidly. In the process of the continuous change of crude oil physical properties, the research and development of new demulsifiers also need to keep up.

[0003] Due to the complex physical properties of crude oil, there are multiple components and substances inside, and the interactions between them are not yet clear. Therefore, the demulsification effect of crude oil demulsifiers is not a definite value. For different crude oils, the demulsification effect of the same demulsifier is different. Conversely, for different demulsifiers, the adaptability to different crude oils is also different. When selecting a demulsifier suitable for a corresponding crude oil, a large number of preliminary experiments are required for sample screening. For example, when demulsifying ultra - thick oil with a viscosity of 9×10 5 mPa·s at room temperature, conventional demulsifiers such as SP169 on the market were used for demulsification, and it was found that the demulsification effect was poor. Under the conditions of 80°C, 3 h, and a dosage of 500 ppm, the average dehydration rate was about 10%, and some demulsifiers had no obvious demulsification effect. Moreover, the versatility of some current demulsifiers is poor, especially for ultra - thick oils.

[0004] Therefore, it is necessary to synthesize a new demulsifier applicable to ultra - thick oils with different viscosities to solve such problems. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a demulsifier applicable to ultra - thick oils with different viscosities, its preparation method and application. The demulsifier of the present invention is a copolymer of butyl acrylate and methoxypolyethylene glycol acrylate. The preparation method of this copolymer is simple, and under the conditions of 80°C and a dosage of 500 ppm, the demulsification effect on different ultra - thick oils at different times can reach more than 96%.

[0006] Term Explanation:

[0007] Room temperature: It has the well - known meaning in the art and refers to 25±5°C.

[0008] The technical solution of the present invention is as follows:

[0009] A demulsifier applicable to ultra-heavy oils with different viscosities, the demulsifier having the structure shown in formula (I):

[0010]

[0011] In formula (I), n is an integer from 10 to 12, x is an integer of (3 - 10)×10 2 and y is an integer of (2.5 - 6)×10 3 .

[0012] According to the present invention, the preparation method of the above-mentioned demulsifier applicable to ultra-heavy oils with different viscosities includes the following steps:

[0013] Add methoxypolyethylene glycol acrylate (PEGMEA) to acetonitrile, after raising the temperature to the reaction temperature, add the initiator solution, and then add butyl acrylate (BA) for reaction to obtain a demulsifier applicable to ultra-heavy oils with different viscosities.

[0014] Preferably according to the present invention, the volume ratio of acetonitrile to the total mass of methoxypolyethylene glycol acrylate (PEGMEA) and butyl acrylate is 1 - 2 mL:1 g.

[0015] Preferably according to the present invention, the initiator is azobisisobutyronitrile (AIBN) or benzoyl peroxide (BPO); the initiator solution is obtained by dissolving the initiator in acetonitrile; the concentration of the initiator solution is 0.001 - 0.05 g / mL.

[0016] Preferably according to the present invention, the mass of the initiator is 0.05 - 1% of the total mass of methoxypolyethylene glycol acrylate (PEGMEA) and butyl acrylate.

[0017] Preferably according to the present invention, the mass ratio of methoxypolyethylene glycol acrylate to butyl acrylate is 6:4 - 2:8.

[0018] Preferably according to the present invention, the butyl acrylate is added dropwise into the system, and the dropping time is 20 - 40 min.

[0019] Preferably according to the present invention, the reaction temperature is 60 - 85°C; the reaction is carried out under a nitrogen atmosphere, and the reaction time is 4 - 16 h.

[0020] Preferably according to the present invention, after the reaction is completed, it further includes a post-treatment step, specifically as follows: place the obtained reaction solution in a dialysis bag, perform dialysis in ethanol, and then remove the solvent and dry to obtain a demulsifier applicable to ultra-heavy oils with different viscosities;

[0021] More preferably, the cut-off molecular weight of the dialysis bag is 1000 - 10000 D; the dialysis time is 72 - 80 h;

[0022] More preferably, the drying is vacuum drying at 70 °C for 12 h.

[0023] According to the present invention, the application of the demulsifier for ultra-heavy oils with different viscosities is used for demulsifying ultra-heavy oils; the viscosity of the ultra-heavy oil at room temperature is 9×10 5 ~1.5×10 6 mPa·s.

[0024] According to the present invention, the post-treatment step is only for obtaining a pure product for convenient testing. It has been confirmed through demulsification experiments that the demulsification effect of the unpurified polymer solution obtained after the reaction is not much different from that of the purified polymer.

[0025] The technical features and beneficial effects of the present invention are as follows:

[0026] 1. Through a large number of experimental screenings, the present invention selects butyl acrylate and methoxypolyethylene glycol acrylate (PEGMEA) as monomers to prepare a copolymer demulsifier. The synergistic effect of the two improves the demulsification effect of the demulsifier. Experiments have shown that for ultra-heavy oil with a room temperature viscosity of 9.3×10 5 mPa·s and a water content of 30%, the copolymer of butyl acrylate and methoxypolyethylene glycol acrylate can achieve a demulsification effect of more than 96% under the conditions of 80 °C, 2 h, and an addition amount of 500 ppm. At the same time, for ultra-heavy oil with a room temperature viscosity of 1.5×10 6 mPa·s and a water content of 50%, a demulsification experiment was carried out, and it was found that the demulsification effect could reach more than 96% at 80 °C for 1 h, and the demulsification time was reduced by half. The demulsifier of the present invention contains a methoxypolyethylene glycol acrylate structural unit. As an amphiphilic monomer, methoxypolyethylene glycol acrylate plays a role in penetrating the oil-water interface film in an emulsion with an oil continuous phase. Its presence makes the polymer easier to aggregate on the oil-water surface, and at the same time enhances the displacement ability of the polymer for the natural surfactant at the oil-water interface. The presence of the butyl acrylate structural unit enhances the diffusion ability of the polymer in the continuous phase. It increases the lipophilicity of the polymer, making it easier to diffuse in the oil phase to reach the vicinity of the oil-water interface where the polymer plays a role.

[0027] 2. The synthesis steps of the demulsifier of the present invention are simple, and the synthesis process does not require a high-temperature and high-pressure environment. Moreover, the monomers have stable properties at normal temperature and pressure, are easy to store and transport, and thus have good application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is the NMR spectrum of the demulsifier prepared in Example 1.

[0029] Figure 2Infrared spectra of the demulsifiers prepared in Examples 1-4 and Comparative Example 1.

[0030] Figure 3 Curves showing the demulsification effect of the demulsifiers prepared in Examples 1-4 and Comparative Example 1 on ultra-heavy oil 1.

[0031] Figure 4 Photos showing the demulsification effect of the demulsifiers prepared in Examples 1-4 and Comparative Example 1 on ultra-heavy oil 1.

[0032] Figure 5 Curves showing the demulsification effect of the demulsifier prepared in Example 3 on ultra-heavy oil 2 at different dosages.

[0033] Figure 6 Photos showing the demulsification effect of the demulsifier prepared in Example 3 on ultra-heavy oil 2 at different dosages.

[0034] Figure 7 Surface activity effect diagrams of the demulsifiers prepared in Examples 1-3 and Comparative Example 1. Detailed implementation manners

[0035] For a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the technical solutions of the present invention are described in detail below, but it should not be construed as a limitation on the scope of implementation of the present invention. The butyl acrylate and methoxypolyethylene glycol acrylate used in the examples are both commercially available and conventional in the art.

[0036] Example 1

[0037] A preparation method of a demulsifier applicable to ultra-heavy oils with different viscosities, comprising the following steps:

[0038] At room temperature, 30 g of methoxypolyethylene glycol acrylate (PEGMEA) and 80 mL of acetonitrile are added to a three-necked flask, stirred and dissolved, and then the three-necked flask is placed in an electrothermal oil bath with magnetic stirring function and heated to 80 °C; 0.25 g of azobisisobutyronitrile (AIBN) is dissolved in 20 mL of acetonitrile to prepare an initiator solution. After the three-necked flask is heated to 80 °C, the initiator solution is added to the three-necked flask, and then 20 g of butyl acrylate (BA) is added dropwise under a nitrogen atmosphere. The dropping time is 30 min. After the dropping is completed, the reaction is continued at 80 °C under a nitrogen atmosphere for 6 h to obtain a colorless transparent viscous liquid; the obtained liquid is placed in a dialysis bag with a molecular weight cut-off of 1000 D and dialyzed in ethanol for 72 h. After dialysis, the solvent is removed using a rotary evaporator, and the obtained product is placed in a vacuum drying oven and vacuum dried at 70 °C for 12 h to obtain a transparent gel-like product, which is the demulsifier applicable to ultra-heavy oils with different viscosities, denoted as PN-64.

[0039] Example 2

[0040] The preparation method of a demulsifier applicable to ultra - heavy oils with different viscosities is as described in Example 1, except that: the mass of methoxypolyethylene glycol acrylate used is 25 g, and the mass of butyl acrylate used is 25 g. The obtained demulsifier applicable to ultra - heavy oils with different viscosities is denoted as PN - 55.

[0041] Example 3

[0042] The preparation method of a demulsifier applicable to ultra - heavy oils with different viscosities is as described in Example 1, except that: the mass of methoxypolyethylene glycol acrylate used is 20 g, and the mass of butyl acrylate used is 30 g. The obtained demulsifier applicable to ultra - heavy oils with different viscosities is denoted as PN - 46.

[0043] Example 4

[0044] The preparation method of a demulsifier applicable to ultra - heavy oils with different viscosities is as described in Example 1, except that: the mass of methoxypolyethylene glycol acrylate used is 10 g, and the mass of butyl acrylate used is 40 g. The obtained demulsifier applicable to ultra - heavy oils with different viscosities is denoted as PN - 28.

[0045] Comparative Example 1

[0046] The preparation method of an ultra - heavy oil demulsifier is as described in Example 1, except that: the mass of methoxypolyethylene glycol acrylate used is 40 g, and the mass of butyl acrylate used is 10 g. The obtained demulsifier applicable to ultra - heavy oils with different viscosities is denoted as PN - 82.

[0047] Example 5

[0048] The preparation method of a demulsifier applicable to ultra - heavy oils with different viscosities is as described in Example 1, except that: the mass of azobisisobutyronitrile used is 0.05 g.

[0049] Example 6

[0050] The preparation method of a demulsifier applicable to ultra - heavy oils with different viscosities is as described in Example 1, except that: the mass of azobisisobutyronitrile used is 0.1 g.

[0051] Example 7

[0052] The preparation method of a demulsifier applicable to ultra - heavy oils with different viscosities is as described in Example 1, except that: the mass of azobisisobutyronitrile used is 0.15 g.

[0053] Example 8

[0054] The preparation method of a demulsifier applicable to ultra - heavy oils with different viscosities is as described in Example 1, except that: the mass of azobisisobutyronitrile used is 0.2 g.

[0055] Example 9

[0056] The preparation method of a demulsifier applicable to ultra - thick oils with different viscosities is as described in Example 1, except that the mass of azobisisobutyronitrile used is 0.3 g.

[0057] Example 10

[0058] The preparation method of a demulsifier applicable to ultra - thick oils with different viscosities is as described in Example 1, except that the mass of azobisisobutyronitrile used is 0.35 g.

[0059] Example 11

[0060] The preparation method of a demulsifier applicable to ultra - thick oils with different viscosities is as described in Example 1, except that the mass of azobisisobutyronitrile used is 0.4 g.

[0061] Example 12

[0062] The preparation method of a demulsifier applicable to ultra - thick oils with different viscosities is as described in Example 1, except that the mass of azobisisobutyronitrile used is 0.45 g.

[0063] Example 13

[0064] The preparation method of a demulsifier applicable to ultra - thick oils with different viscosities is as described in Example 1, except that the mass of azobisisobutyronitrile used is 0.5 g.

[0065] Example 14

[0066] The preparation method of a demulsifier applicable to ultra - thick oils with different viscosities is as described in Example 1, except that the temperature is raised to 60 °C.

[0067] Example 15

[0068] The preparation method of a demulsifier applicable to ultra - thick oils with different viscosities is as described in Example 1, except that the temperature is raised to 65 °C.

[0069] Example 16

[0070] The preparation method of a demulsifier applicable to ultra - thick oils with different viscosities is as described in Example 1, except that the temperature is raised to 70 °C.

[0071] Example 17

[0072] The preparation method of a demulsifier applicable to ultra - thick oils with different viscosities is as described in Example 1, except that the temperature is raised to 75 °C.

[0073] Example 18

[0074] The preparation method of a demulsifier applicable to super heavy oil with different viscosities is as described in Example 1, except that: the temperature is raised to 85°C.

[0075] Example 19

[0076] The preparation method of a demulsifier applicable to super heavy oil with different viscosities is as described in Example 1, except that: the reaction time is 4 h.

[0077] Example 20

[0078] The preparation method of a demulsifier applicable to super heavy oil with different viscosities is as described in Example 1, except that: the reaction time is 8 h.

[0079] Example 21

[0080] The preparation method of a demulsifier applicable to super heavy oil with different viscosities is as described in Example 1, except that: the reaction time is 10 h.

[0081] Example 22

[0082] The preparation method of a demulsifier applicable to super heavy oil with different viscosities is as described in Example 1, except that: the reaction time is 12 h.

[0083] Example 23

[0084] The preparation method of a demulsifier applicable to super heavy oil with different viscosities is as described in Example 1, except that: the reaction time is 14 h.

[0085] Example 24

[0086] The preparation method of a demulsifier applicable to super heavy oil with different viscosities is as described in Example 1, except that: the reaction time is 16 h.

[0087] Test Example

[0088] 1. Nuclear magnetic resonance characterization

[0089] In order to identify whether the synthesized polymer conforms to the structure of the designed product, the structure of the product of Example 1 was determined by Bruker AVANCE400MHz NMR, and the determination results are as Figure 1 shown. Among them, δ: the -CH3 proton peak on the side chain BA is at 0.96 ppm, δ: the methylene proton peaks of the side chain BA are at 1.34 and 1.65 ppm, and δ: the terminal methyl proton peak of the side chain PEGMEA is at 3.34 ppm. Among them, δ: the methylene proton peak of the EO unit on the side chain PEGMEA is at 3.64 ppm, and δ: the methylene proton peak of the side chain BA close to -O- is at 4.12 ppm.

[0090] 2. Gel chromatography column

[0091] The molecular weights of the demulsifiers prepared in Examples 1-4 and Comparative Example 1 were determined using an Agilent PL-GPC50. The results are shown in Table 1 below:

[0092] Table 1 Molecular weights of the demulsifiers prepared in Examples 1-4 and Comparative Example 1

[0093]

[0094] In the demulsifiers prepared in Examples 1-4 and Comparative Example 1, n = 12, and the values of x and y are shown in Table 2.

[0095] Table 2

[0096] Compound x y PN-82 <![CDATA[1.94×10 3 > <![CDATA[2.05×10 3 > PN-64 <![CDATA[9.77×10 2 > <![CDATA[2.80×10 3 > PN-55 <![CDATA[6.62×10 2 > <![CDATA[2.79×10 3 > PN-46 <![CDATA[6.61×10 2 > <![CDATA[4.18×10 3 > PN-28 <![CDATA[3.47×10 2 > <![CDATA[5.86×10 3 >

[0097] 3. Infrared spectrum

[0098] The infrared spectra of the demulsifiers prepared in Examples 1-4 and Comparative Example 1 are as Figure 2 shown. The two stretching vibration peaks at 2778 cm -1 and 2931 cm -1 are for the methylene and methine groups on the main chain and side chains of the polymer. The stretching vibration peak at 1742 cm -1 is for the ester bond, and in the range of 546 cm -1 to 1424 cm -1 centered at 1160 cm -1 are the stretching vibration peaks of ether bonds at different positions on the polymer side chain.

[0099] 3. Demulsification effect

[0100] According to the "SY / T 5281-2000 Detection Method for the Performance of Crude Oil Demulsifiers (Bottle Test Method)", the demulsification effect was characterized. The oil sample was super heavy oil 1 (room temperature viscosity 9.3×10 5 mPa·s, water content 30%). It was found that under the conditions of 80°C, 2 h, and a dosage of 500 ppm, the demulsification effect of Example 3 could reach 96%. As Figures 3-4 shown.

[0101] Subsequently, a demulsification experiment was carried out using super heavy oil 2 (room temperature viscosity 1.5×10 6 mPa·s, water content 50%). Under the conditions of 80°C, 2 h, and a dosage of 500 ppm, the demulsification effect of Example 3 could reach 96%. As Figures 5-6 shown. It can be seen that the water quality separated from the two oil samples is different, one is turbid and the other is relatively transparent, which is caused by the nature of the oil samples themselves and has little to do with the demulsifier.

[0102] 4. Surface tension

[0103] The surface tension of the copolymer was measured using a KRUSS-K100 surface tensiometer from Germany, and its CMC value was speculated. From Figure 7 It can be seen that with the increase in the feeding amount of butyl acrylate, the ability to reduce the surface tension first increases and then decreases. When the feeding ratio is 5:5, the surface tension can be lowered to a minimum of 40 mN / m. When the feeding ratio reaches 4:6, the ability to reduce the surface tension decreases. This is because the increase in hydrophobic groups results in fewer molecules aggregating at the water surface and more likely to form micelles in the aqueous phase, leading to a weakened ability to reduce the surface tension.

[0104] The CMC value was speculated based on the information in the figure, and the CMC values of the samples were all between 300 mg / L and 400 mg / L.

Claims

1. A demulsifier applicable to ultra-heavy oils with different viscosities, characterized in that, The demulsifier has the structure shown in formula (I): In formula (I), n is an integer from 10 to 12, x is an integer of (3 - 10)×10 2 and y is an integer of (2.5 - 6)×10 3 .

2. The preparation method of the demulsifier for super heavy oil with different viscosities according to claim 1, comprising the following steps: Add methoxypolyethylene glycol acrylate into acetonitrile, raise the temperature to the reaction temperature, add the initiator solution, and then add butyl acrylate to react to obtain the demulsifier for super heavy oil with different viscosities.

3. The preparation method of the demulsifier applicable to super heavy oil with different viscosities according to claim 2, characterized in that, The volume ratio of the acetonitrile to the total mass of methoxypolyethylene glycol acrylate and butyl acrylate is 1 - 2 mL:1 g.

4. The preparation method of the demulsifier applicable to super heavy oil with different viscosities according to claim 2, characterized in that, The initiator is azobisisobutyronitrile or benzoyl peroxide; the initiator solution is obtained by dissolving the initiator in acetonitrile; the concentration of the initiator solution is 0.001 - 0.05 g / mL.

5. The preparation method of the demulsifier applicable to super heavy oil with different viscosities according to claim 2, characterized in that, The mass of the initiator is 0.05 - 1% of the total mass of methoxypolyethylene glycol acrylate and butyl acrylate.

6. The preparation method of the demulsifier applicable to ultra-heavy oil with different viscosities according to claim 2, characterized in that, The mass ratio of methoxypolyethylene glycol acrylate to butyl acrylate is 6:4 - 2:8; the butyl acrylate is added dropwise into the system, and the dropping time is 20 - 40 min.

7. The preparation method of the demulsifier applicable to ultra-heavy oil with different viscosities according to claim 2, characterized in that, The reaction temperature is 60 - 85 °C; the reaction is carried out under a nitrogen atmosphere, and the reaction time is 4 - 16 h.

8. The preparation method of the demulsifier applicable to super heavy oil with different viscosities according to claim 2, characterized in that, After the reaction is completed, it also includes a post-treatment step, specifically as follows: Place the obtained reaction solution in a dialysis bag, dialyze it in ethanol, then remove the solvent and dry it to obtain the demulsifier for super heavy oil with different viscosities.

9. The preparation method of the demulsifier applicable to ultra-heavy oil with different viscosities according to claim 8, characterized in that, The cut-off molecular weight of the dialysis bag is 1000 - 10000 D; the dialysis time is 72 - 80 h; the drying is vacuum drying at 70 °C for 12 h.

10. Use of the demulsifier applicable to ultra-heavy oils with different viscosities according to claim 1 for demulsifying ultra-heavy oils; the viscosity of the ultra-heavy oil at room temperature is 9×10 5 ~1.5×10 6 mPa·s.

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